package com.hmdp.service.impl;

import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.MQ.MQSender;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.Collections;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private MQSender mqSender;
    //初始化lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    @Override
    public Result seckillVoucher(Long voucherId) {

        //1.获取用户id
        Long userId = UserHolder.getUser().getId();

        //2.执行lua脚本
        Long result = stringRedisTemplate.execute(SECKILL_SCRIPT, Collections.emptyList(), voucherId.toString(), userId.toString());
        //判断返回值
        int r = result.intValue();
        if (r != 0) {
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        long orderId = redisIdWorker.nextID("order");

        //创建订单并发送到消息队列
        VoucherOrder voucherOrder = new VoucherOrder();
        voucherOrder.setId(orderId);
        voucherOrder.setVoucherId(voucherId);
        voucherOrder.setUserId(UserHolder.getUser().getId());

        mqSender.sendSeckillMessage(JSONUtil.toJsonStr(voucherOrder));
        return Result.ok(orderId);
    }


    @Transactional
    public Result createVoucherOrder(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        synchronized (userId.toString().intern()) {
            // 5.1.查询订单
            int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
            // 5.2.判断是否存在
            if (count > 0) {
                // 用户已经购买过了
                return Result.fail("用户已经购买过一次！");
            }

            // 6.扣减库存
            boolean success = seckillVoucherService.update().setSql("stock = stock - 1") // set stock = stock - 1
                    .eq("voucher_id", voucherId).gt("stock", 0) // where id = ? and stock > 0
                    .update();
            if (!success) {
                // 扣减失败
                return Result.fail("库存不足！");
            }

            // 7.创建订单
            VoucherOrder voucherOrder = new VoucherOrder();
            // 7.1.订单id
            long orderId = redisIdWorker.nextID("order");
            voucherOrder.setId(orderId);
            // 7.2.用户id
            voucherOrder.setUserId(userId);
            // 7.3.代金券id
            voucherOrder.setVoucherId(voucherId);
            save(voucherOrder);

            // 7.返回订单id
            return Result.ok(orderId);
        }
    }
}
